Response of Ants at Harvard Forest to Climate Change

Response of Ants at Harvard Forest to Climate Change﻿

Project Summary:

Experimental field studies are needed to understand the consequences of global climatic change for local community structure and associated ecosystem processes. We propose to use large open-top environmental chambers to simultaneously manipulate air and soil temperatures using a statistically powerful and cost-efficient response-surface (regression) design at two field sites situated in northern and southern temperate mixed hardwood forests in eastern North America (Harvard Forest in Massachusetts, Duke Forest in North Carolina). The proposed field manipulations will reveal the effects of temperature increases on the populations, communities, and associated ecosystem services of assemblages of ground-foraging ants. Ants are a model taxon for studying effects of global climatic change because they comprise the dominant fraction of animal biomass in many terrestrial communities and because they provide essential ecosystem services, including soil turnover, decomposition, and seed dispersal. The experiment is designed to test three predictions:

Projected atmospheric warming will lead to declines in ant species abundances at the warmer, southern extent of their ranges in the US. Conversely, projected atmospheric warming will lead to increases in abundance or range extensions of ant species at the cooler, northern extent of their ranges in the US.

Warming will change the relative abundance and composition of ant communities, and will lead to the loss of ant biodiversity.

Warming will potentially diminish ecosystem processes and services provided by ants, particularly with respect to the dispersal of seeds.

Twelve open-top chambers at each site which will each be exposed to one of four levels of air temperature increases, ranging from no change (ambient conditions) to 8 degrees C (commensurate with some IPCC climate model forecasts for the year 2100). The experiment will run for 3 consecutive years of continuous warming. The response variables measured will include ant activity, population densities and colony sizes of focal species, ant community diversity and species composition, and rates of seed dispersal and predation as mediated by ants. This study will provide an experimental test of the hypothesis that species at the northern and southern boundaries of their ranges will respond predictably to climatic change. In addition, this research will further establish ants as a model taxon for the study of climatic change.

People:

Design and construction:

The Harvard Forest ant-warming experiment ("Warm Ants") will be located within Harvard Forest's Prospect Hill tract in Petersham, Massachusetts. This heavily instrumented ~500 ha area is the focus of the Harvard Forest Long Term Ecological Research (LTER) site. In addition to the Warm Ants project, other long-term research installations on the Prospect Hill tract include three eddy-covariance towers (the EMS tower, the Little Prospect Hill tower, and the Hemlock tower); the Chronic Nitrogen addition experimental plots; a soil warming experiment; a soil warming x nitrogen addition factorial experiment; headwater stream gauges; and the prototype of the Hurricane Pull-down experiment. Shaler Hall (the headquarters of the Harvard Forest), an analytical lab, greenhouse facilities, student dormitories, and short-term housing for visiting researchers are at the southwest corner of the Prospect Hill tract.

The Warm Ants project is co-located with another DOE-supported project examining responses of seedlings and saplings of forest trees to atmosphericwarming ("Hot Plants"). Nine of the Hot Plants chambers and all twelve of the Warm Ants chambers are located in the understory of an ~80-year-old mixed hardwood forest. An additional nine Hot Plants chambers are located in a small forest gap at the north end of the site.

Click here for a detail map of the layout of the ant warming plots.

Click here for a detail map of the layout of the plant warming plots in the gap.

January 27 - Visitors check out the site. Left to right: Rebecca Montgomery (University of Minnesota, Mark Van Scoy (Harvard Forest Engineer), Onno Muller (Tohoku University, Japan), and Masahiro Nakamura (Hokkaido University, Japan). Rebecca is co-PI of another DOE-funded air-warming experiment, the Boreal Forest Warming at an Ecotone in Danger (B4WARMED) project. Masahiro works on soil and branch warming experiments at the Japan LTER site at the Tomakomai Experimental Forest Research Station in Hokkaido. Onno is a plant ecophysiologist interested in climate change and distribution of broad-leaved evergreens.